A function to splice strings.

stringSplice.js

// Usage : stringSplice('my string', 2, 0, ' awesome');
// -> 'my awesome string'
//
// How to extend the native string prototype (if you want):
// String.prototype.splice = function () {
//  var args = [].slice.call(arguments);
//  return stringSplice.apply(null, [this.valueOf()].concat(args));
// };

function stringSplice(baseString, start, length, newString) {
  var a = baseString.substr(0, start);
  var b = baseString.substr(start + length, baseString.length - start - length);
  return a + newString + b;
};